Lawrence Hong, 27, Josh Hunter, 23, Kaitlin Perras, 23, Zackariah Rathwell, 21, and Jordan Segura, 22, have been identified as the victims in the attack, which took place at a house party celebrating the last day of university classes.

Mr de Grood praised his son and said he ran to raise money for charity and planned to attend the University of Calgary's law school in the autumn.

"Just like you, we struggle to understand what happened," he said, adding the family had received an "outpouring of support".

"We will never recover from this, but the collective support has helped ease some of the pain."

Psychiatric evaluation

Calgary police said their investigation focused on the younger Mr de Grood's actions before the attack.

"There didn't seem to be any precursors to this as far as any grudge or any vendetta or anything that would result in a motivation for this attack," Calgary police spokesman Kevin Brookwell told reporters on Thursday.

Mr de Grood is being held at a secure psychiatric facility. A hearing is scheduled for Tuesday.

A separate Crown prosecution team from the province's capital of Edmonton will be appointed because of his father's position with the police force, CBC News reported.

A lawyer for the family has said he thought the prosecutor would request a psychological assessment at the hearing, but says he is not aware of any mental health concerns.